How to use -moz-appearance scrollbar? (CSS)

So we know that you can actually customize your scrollbar using CSS in Chrome and IE(I think..). What about Firefox? They seem to have this -moz-appearance property that allows you to customize your scrollbar. (Some resources) http://ift.tt/1i1dyor http://ift.tt/1cLXMM8.

My question is, how do I do it? Perhaps showing me an example code will help.

Thanks for your time :)